Cannot reprogram B-L072Z LoRaWAN Discovery board.

[ty.locke]

I have a B-L072Z LoRa dev board that I am unable to reprogram. ST-Link drivers are installed and the device communicates to my PC terminal via the virtual COM port without issue. When I attempt to flash the board with a new binary, it appears to reprogram (file begins to copy and RG LED flashes); however, once completed, the default example is still running on the board. I tried disconnecting and resetting the board a few times. I also compiled the binary again and tested programming another board just to make sure there was nothing wrong with the file.

I have several of the discovery kits and they all reprogram seamlessly through the ST Link except this one particular unit.

Has anyone else seen this issue? Any suggestions?

[Tesla DeLorean]

Check the CN8 jumpers are present. ​

[ty.locke]

Hi Clive,

I've had this issue pop up with a pair of boards and wonder if you have even seen similar behavior. Both boards had no issues out of the box but after a few months of use and many rounds of re-programming, I can no longer program the boards.

When I plug into the PC via USB I receive fail.txt in the virtual drive indicating that the STLink cannot halt the MCU.

Using the STLink Utility I tried updating the STLink firmware (which was successful), connecting to the device under reset, and pull-ing Boot0 high; however, I am completely unable connect with the MCU to reprogram it or erase the chip.

Have you observed any similar behavior with STM32 devices?

This is a bit worrisome for me and gives me pause when considering these MCUs for a custom board.

[Tesla DeLorean]

Been using these DISCO boards for several years without such incidents. And also used several other boards using the Murata modules.

If the BOOT0:High, connect under reset tricks don't work you'll need to move on to power supply or pin level connectivity issues.

CMOS devices have sensitivity to static (ESD), and silicon works as a better fuse than fuses do, so it's not exactly uncommon for people to destroy devices in assorted ways.

[ty.locke]

Got it.

Power supplies have checked out so I'll have to see if there's any other pin level issues.

It's also quite possible that the devices were subject to ESD so that may potentially be the root cause.

Thanks for the quick reply.